The best way to stay dry is to wear waterproof clothing. While most synthetic fabrics still insulate when wet, being wet diminishes their ability to keep you warm.

Staying dry with waterproof clothing is a sure fire way to stay comfortable

by John Brown, HaveFunBiking.com

Staying dry is the most critical and challenging part of riding when biking in the rain as spring arrives. The best way to keep warm and dry is to wear waterproof clothing. While most synthetic fabrics still insulate when wet, being damp diminishes their ability to keep you warm. Therefore, a waterproof jacket and pants are a great way to start, but waterproof socks and gloves make the outfit complete. While many materials are naturally waterproof, once perforated with stitching, zipped closed with generic zippers, and left to be loose at all the cuffs, their waterproofing goes out the window. Before you go out and buy anything labeled “waterproof,” read on to understand that all waterproofing is not the same.

Waterproof Clothing and Gear for Staying Dry

To keep water out, look for waterproof clothes that have sealed or welded seams (see image). Also, look for waterproof zippers (pictured) or large flaps that prevent water from driving through the zipper. Make sure all the cuffs are adjustable enough to be snuggled tight against your skin.

Examples of cycling clothes with taped seams (Left), welded seams (Center), and a waterproof zipper (Right)

A waterproof garment is measured in mm of fluid. For example, a fabric that was 5,000  mm waterproof is tested as follows. The fabric is placed over the end of a long tube. Following that, the tube is filled with 5,000 mm of water and the fabric needs to support the pressure without leaking. Take a look at the table below for a quick reference.

Rating Resistance Weather Conditions
0 mm – 1,500 mm Water-resistant/snowproof Dry conditions or very light rain
1,500 mm – 5,000 mm Waterproof Light to average rain
5,000 mm – 10,000 mm Very Waterproof Moderate to heavy rain
10,000 mm- 20,000 mm Highly Waterproof Heavy rain

 Breathe Sweat Out

In addition to measuring waterproofness, textiles are also measured for their ability to breathe water vapor out. Breathable means that water vapor (sweat) being produced by your body can escape through the fabric. Breathable fabrics work because water vapor is smaller than water droplets. In order to breathe, the material will be perforated with holes small enough to stop water droplets from getting in, but large enough to allow water vapor to escape.

Breathability is important because, as far as insulation is concerned, it’s just as bad to get soaked with sweat as with rain. Therefore, using a breathable material in tandem with base layers designed to pull moisture off your skin is a sure-fire way to stay dry and warm.

Breathability is expressed in terms of how many grams (g) of water vapor can pass through a square meter (m2) of the fabric from the inside to the outside in a 24 hour period. To that effect, the larger the number, the more breathable the fabric. For example, a coat with 5,000 gsm breathability, 5,000 grams of water pass through a square meter of the fabric.

Waterproof even when it isn’t raining

During the spring thaw snow melts during the day and freezes again at night. In my commutes, during the thaw, I focus on wearing waterproof clothing to keep warm. The rivers of salty water I end up riding through would soak any non-waterproof clothing rendering it useless.

When Waterproof is Not Important

As the temperature rises, waterproofing becomes less and less important. It’s less important because, at a certain temperature, waterproof materials cannot breathe enough to keep you dry. Therefore, if it rains hard enough, and it’s warm enough, you’re going to get wet.

In the spring and fall, be sure to have your waterproof gear ready. The cool temps and wet conditions can be very dangerous if you aren’t prepared. Being dry is the #1 way to maintain your comfort and safety while riding in inclement conditions.

About John Brown, the author

As a lifelong cyclist and consummate tinkerer, John operates Browns Bicycle in Richfield, MN. It all started for him in grade school when the bike bug bit and that particular fever is still there. Now, and over the past thirty years, he has worked at every level in the bike industry. Starting, like most, sweeping floors and learning anything he could about bikes. He eventually graduated as a service manager and then to a store manager.  Through the years, he has spent extensive time designing and sourcing bicycles and parts for some of the largest bike companies in the world. All the while focusing on helping as many people as possible enjoy the love of riding a bike. In that pursuit, he has taught classes (both scheduled and impromptu) on all things bikes. John also believes in helping every rider attain their optimal fit on the bike of their dreams. Please feel free to stop in any time and talk about bikes, fit, parts, or just share your latest ride. You can also see more of John’s tricks and tips on the Brown Bicycle Facebook Page.

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